Method of making heat resistant flexible hose



Dec 1 1965 H. E. FRITZ ETAL METHOD OF MAKING HEAT RESISTANT FLEXIBLEHOSE Original Filed May 19, 1960 INVENTORS E Y mm m K 5 WW N/ N A0 Hn 0L E. T we w m R .M P S A M K H Dw Y YWWHLRKMMR R D NFE R E DB AMR I ROOHRFRFGR United States Patent 3,223,565 METHOD OF MAKENG HEAT RESISTANTFLEXEBLE HUSE Harry E. Fritz, Philadelphia, Pa., Raymond A. Gallagher,Gibbsboro, N.J., Frederick M. Galloway and Richard M. Kerr, Langliorne,Pa., Frank B. Plumb, Haddonfield, N..l., and Godfrey ll. Rittenhouse,Feasterville, and Robert H. Sinnanlon, Huntingdon Valley, Pa, assignorsto H. K. Porter Company Inc, Pittsburgh, Pa., and Thermoid Division,Quaker Works, Philadelphia, Pa., a corporation of Delaware Qriginalapplication May 19, 1960, Ser. No. 30,126, now Patent No. 3,117,597,dated Jan. 14, 1964. Divided and this application Aug. 5, 1963, Ser. No.301,231

2 Claims. (Cl. fi-86) This application is a division of applicationSerial No. 30,126, now Patent 3,117,597.

This invention relates to heat resistant flexible nonmetallic hose, andespecially to hose of the kind mentioned in the application, Serial No.744,580, now Patent 3,073,- 353, of Godfrey I. Rittenhouse, one of thepresent inventors, for United States Letters Patent for AbrasionResistant Ventilating Jacket for Jet Engine Starter Hoses, the saidjacket being suitable for use with the hose herein disclosed.

Aircraft jet engines are commonly activated by injecting hot air intothem at high velocity through ports provided for the purpose to whichflexible hose is connected to conduct the air from a suitable sourcesuch as a motor vehicle or trailer carrying appropriate generatingapparatus.

Heretofore the hose has been made of heat resistant elast-omericmaterials of the silicone type reinforced with a heavy woven fabricouter jacket of the structural characteristics of the woven cottonjackets commonly used for fire hose but made of yarns comprising fibersof a polyethylene tcrephthalate such as Dacron marketed by E. I. du Pontde Nemours Company of 'Wilmington, Delaware. Such hose, however,deteriorates rapidly at temperatures exceeding 500 F. whereas air heatedto 615 F. or more is now being employed for jet engine starting.

It is a principal object of this invention therefore to provide aflexible hose capable without excessive deterioration of conducting airheated to 615 F. or higher for long periods, or for relativelyindefinitely repeated shorter ones which are more usual in jet enginestarting service.

A further object is to provide a hose comprising a heat resistantelastomeric inner lining and a strong outer reinforcement of textilefabric with heat insulating intermediate layers disposed between themwhereby the outer reinforcement preferably comprising Dacron yarn isprotected from excessive heating during passage of highly heated airthrough the hose.

Other objects, purposes and advantages of the invention will hereaftermore fully appear or will be understood from the following descriptionin which reference will be had to the accompanying drawing wherein:

FIG. 1 is a fragmentary side elevation with successive layers brokenaway of a starter hose embodying the invention;

FIG. 2 is a fragmentary diagrammatic much enlarged plan view of a coatedfabric used in making the hose;

FIG. 3 is a fragmentary much enlarged section showing the relationshipof the warp and filler yarns in certain fabric layers of the hosecorresponding to a section on line 3-3 in FIG. 1 and with the relativethickness of the elastomeric impregnant of the fabric considerablyexaggerated;

FIG. 4 is a transverse section of the hose on line 4-4 in FIG. 1,relative thicknesses being exaggerated to some extent in all saidfigures;

3,223,565 Patented Dec. 14, 1965 FIG. 5 is an enlarged fragmentary viewcorresponding to FIG. 2 but showing a typical abutting relationship oftwo adjacent areas of such fabric in the hose.

Referring now more particularly to the drawing, the hose as showntherein comprises a plurality of layers each having specialcharacteristics conjointly contributing to the capacity of the hose as.a whole to serve its intended function, including an elastomeric innerlining layer 1, intermediate heat insulating layers 2, 3, an outerelast-omeric layer 4 and an outer fabric reinforcing layer 5 each ofwhich, individually, will now be described in conjunction withdisclosure of a preferred method of making the hose.

The tubular inner lining layer 1 of a highly heat resistant siliconeelastomer or the like, is preferably seamlessly extruded in the uncuredstate and partially cured in any convenient manner as by subjecting itto about 268 F. for 20 minutes. Then a length of this tube, say 30 or60' long and about 3 /2" ID. with wall thickness about 0.0625", isplaced about a cylindrical mandrel M, preferably a hollow metal one ofat least corresponding length and diameter to snugly fit in the tubehaving end closures (not shown) equipped for circulation of live steamunder considerable pressure through its interior. For convenience themandrel, carrying the fully or partially cured tube 1 is mounted in alathe or other apparatus whereby it can be rotated while the firstinsulating layer 2 of a material hereafter more fully described is woundhelically on tube 1 as a strip the width of which is so adjusted to theouter diameter of the tube that when successive convolutions of thestrip abut, the helical joint between their opposed edges defines ahelix making an angle of approximately 54 with respect to the axis A ofthe mandrel as indicated in FIG. 1. Next a strip of like material iswound in substantially the same manner over the first to form the secondinsulating layer 3 which, however, is spiraled to the opposite hand,i.e., so that its abutting edges define a helix of opposite angularity.There is then applied over layer 3 uncured heat resistant siliconeelastomer either as a helically wound strip or as a butt jointed sheetto form layer 4 over which there is braided with the aid of a braider ofusual type Dacron yarn to form fabric reinforcing layer 5.

The yarns for reinforcing layer 5 are desirably primed with a thinsolution of silicone and wound on the bobbins of the braider in groupsof six for braiding as strips or fiat warps forming on the surface ofthe hose a pattern of reinforcement resembling a coarse twill weave, therelatively heavy 4-ply high twist yarns being maintained under tensionpreferably of 6-9 lbs. thus tending to imbed them somewhat in thesurface of the underlying uncured elastomeric layer 4 to which theybecome intimately bound during a subsequent operation.

After braiding on reinforcing layer 5 there is applied temporarily andunder tension a Wrapping of nylon or other suit-able tape (not shown) toexert radial inward or centripetal pressure on the reinforcement andhence all other underlying layers, and live high pressure steam or othersuitable heating medium is introduced to the interior of the mandrel toheat it preferably to about 300 P. which temperature is maintained forabout an hour or such other time as may be required to complete thecuring of the el-astomeric components of the hose.

The pressure of the temporary tape wrapping against the outer Dacronreinforcement during this curing step while the underlying silicone isrelatively soft in conjunction with the heat-induced shrinking of theDacron yarns causes the latter to become substantially embedded in orimpregnated with the silicone, which at points exudes through the fabricforming a virtually inseparable bond therewith while the same forcestend to bond firmly together all other hose components into a unitarywhole.

After the curing has been completed the heating is discontinued, thetemporary tape removed, and the hose, first artificially cooled ifpreferred, is withdrawn from the mandrel, its ends are trimmed squareand end couplings applied to enable it to be placed in service.

Reference has herein been made to the fabric of which intermediateinsulating layers 2, 3 are composed and which is rep-resented onmagnified scale in FIGS. 2 and 3. As shown therein it comprisesrelatively large diameter 3-ply low twist warp yarns 6 connectedtogether by relatively widely spaced and considerably smaller diameterfiller yarns 7. The warp yarns 6 are made of glass or other refractoryinorganic fibers While the small filler yarns 7 may be single ply lowtwist Dacron or other organic thread interwoven with the warp yarns in aweave comparable to that of standard tire cord fabric in which, as inthe glass-Dacron fabric we employ, the filler yarns are only just strongenough and appropriately spaced to hold the warp yarns closely togetherwithout imparting material transverse tensile strength to the fabric.

For preparing the strips used to form layers 2, 3 of the hose a fabricof the kind just described first primed with a suitable silicone primeris coated with about 0.0625" of an uncured silicone type heat resistantelastomer, preferably by a skimming operation in which the elastomer iscalendered under pressure onto one surface of the fabric as it passesthrough calendaring rolls whereby the fabric becomes permeated with theelastomer which protrudes into the fabric interstices from that face towhich it is initially applied to or almost to the opposite face, beingrepresented by the elastomeric material 8 in the fabric illustratedparticularly in FIG. 3. This material is produced in lengths sufiicientto extend in a single uninterrupted helix from end to end of the hosewhereby as the glass fiber-s in the warp yarns are desirably of thecontinuous filament type, each of layers 2, 3 comprises a multiplicityof glass fibers extending helically the full length of the hose.

The Dacron relatively finer filler yarns 7 (not shown in FIG. 1) asnoted, primarily function to hold the warp yarns together laterally, afunction no longer so essential after the fabric has been calendered tothe elastomeric material 8, and when the hose in which they areincorporated is subjected to intense heat they either fuse and thusconform to the shape of the glass warp yarns with which they areinterwoven, or substantially disappear. This materially contributes tothe 'serviceability of the hose since in all-glass-fiber woven fabricsfailures occur principally at the points at which the warp [and filleryarn-s cross and result from bending of the relatively brittle componentfibers beyond their elastic limits. With filler yarns of Dacron,however, initial severe bending of the glass fibers in the Warp yarns isminimized and later eliminated when the Dacron is heated to fusionduring testing or, at the latest, shortly after the hose has been placedin service.

These closely spaced glass fibers are heat resist-ant and relativelynon-conducting in respect to heat so that hose made as herein describedwill convey air heated to 615 F. virtually indefinitely withoutattaining a skin temperature in excess of about 325 P. which is wellwithin the capacity of the Dacron of the outer reinforcement towithstand without appreciable loss of tensile strength.

The silicone coating skimmed on the strips forming layers 2, 3 isusually faced inwardly in both layers although obviously both may befaced outwardly or oppositely faced if desired, while in some instancesglass- D-acron fabric skimmed on both faces may be used. It ispreferable, however, the opposed helices of glass fibers be separated bya thin film of the silicone elastome-r i1upregnant to avoid abrasivecontact between them and can thus contribute substantially to thebursting strength of the hose without impairing its flexibility;adjacent individual yarns in each layer are isolated from each other andprotected against internal abrasion by the elastomer forced between themduring the skimming operation.

While we have herein illustrated and described with considerableparticularity -a preferred embodiment of our hose produced from certainmaterials by the practice of the specific steps set forth in detailherein, we do not desire or intend thereby to be limited or confinedthereto or thereby in any way, as the characteristics of our hose aresubstantially independent of the specific procedures employed in itsmanufacture which may differ in principle and in detail from those weconveniently employ, while changes and modifications in the form,construction, composition, relationship and arrangement of the severalcomponents of our hose will readily occur to those skilled in the artand may be utilized if desired without departing from the spirit andscope of the invention as defined in the appended claims.

Having thus described our invention, we claim and desire to protect byLetters Patent of the United States:

1. The method of making a heat resistant flexible hose which comp-risesextruding an uncured elastomer silicone tube, at least partially curingsaid tube, disposing the tube on a hollow tubular mandrel, impregnatingfabric of tire cord fabric weave having glass fiber warp yarns andpolyethylene terephthalate filler yarns with an uncured siliconeelastomer, winding a strip of the impregnated fabric helically about themandrel-mounted tube with the edges of the strip in abutting relation,Winding thereabout a second layer of like fabric in a correspondinghelix of opposite hand, enveloping the second impregnated fabric layerwith a silicone elastomer, braiding a reinforcing layer of polyethyleneterephthalate .yarns thereabout, subjecting the components on themandrel to radially inward pressure While directing a heating mediuminto the mandrel to thereby cure the elastomeric components of the hoseand shrink the polyethylene terephthalate components thereof, thenrelieving said pressure and separating the mandrel from the hose.

2. A method as defined in claim 1 in which the impregnated fabric layersare wound respectively in oppositely directed helices approximating 54to radial planes containing the hose axis.

References Cited by the Examiner UNITED STATES PATENTS 2,652,093 9/1953Burton 156-86 2,833,313 5/1958 Penman 138125 2,988,130 6/1961Rittenhouse 15686 3,062,241 11/1962 Brumbach.

EARL M. BERGERT, Primary Examiner.

1. THE METHOD OF MAKING A HEAT RESISTANT FLEXIBLE HOSE WHICH COMPRISESEXTRUDING AN UNCURED ELASTOMER SILICONE TUBE, AT LEAST PARTIALLY CURINGSAID TUBE, DISPOSING THE TUBE ON A HOLLOW TUBULAR MANDREL, IMPREGNATINGFABRIC OF TIRE CORD FABRIC WEAVE HAVING GLASS FIBER WARP YARNS ANDPOLYETHYLENE TEREPHTHALATE FILLER YARNS WITH AN UNCURED SILICONEELASTOMER, WINDING A STRIP OF THE IMPREGNATED FABRIC HELICALLY ABOUT THEMANDRELL-MOUNTED TUBE WITH THE EDGES OF THE STRIP IN ABUTTING RELATION,WINDING THEREABOUT A SECOND LAYER OF LIKE FABRIC IN A CORRESPONDINGHELIX OF OPPOSITE HAND, ENVELOPING THE SECOND IMPREGNATED FABRIC LAYERWITH A SILICONE ELASTOMER, BRAIDING A REINFORCING LAYER OF POLYETHYLENETEREPHTHALATE YARNS THEREABOUT, SUBJECTING THE COMPONENTS ON THE MANDRELTO RADIALLY INWARD PRESSURE WHILE DIRECTING A HEATING MEDIUM INTO THEMANDREL TO THEREBY CURE THE ELASTOMERIC COMPONENTS OF THEHOSE AND SHRINKTHE POLYETHYLENE TEREPHTHALATE COMPONENTS THEREOF, THEN RELIEVING SAIDPRESSURE AND SEPARATING THE MANDREL FROM THE HOSE.